Image pickup apparatus and method for controlling same

Active Publication Date: 2013-12-12
CANON KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a focus adjustment apparatus that can quickly and accurately adjust the focus of a camera without being affected by changes in the position of the camera's target. This results in faster and more efficient autofocus, and can improve the overall quality of the captured images.

Problems solved by technology

When the object enters or leaves a focus detection area as the object moves (object changes position) or a defocused state of the object changes during the scanning operation (e.g., due movement of the camera), the object changes during an AF operation so that the object is difficult to accurately focus on.
When the AF time is lengthened, the reliability of an AF evaluation result is damaged if the object moves.
Therefore, the AF calculation load is large.

Method used

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  • Image pickup apparatus and method for controlling same
  • Image pickup apparatus and method for controlling same
  • Image pickup apparatus and method for controlling same

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Embodiment Construction

[0025]Various exemplary embodiments, features, and aspects of the invention will be described in detail below with reference to the drawings.

[0026]A first exemplary embodiment of the present invention will be described in detail below with reference to FIGS. 1 to 6. FIG. 2 is a block diagram illustrating an example of a schematic configuration of an image pickup apparatus including a focus adjustment apparatus according to the exemplary embodiment of the present invention. While the image pickup apparatus includes a digital still camera and a digital video camera, the present invention is not limited to these. As long as an image pickup apparatus acquires an optical image by focusing light onto an image sensor and by photoelectrically converting the light incident on the image sensor into an electric signal using two-dimensional array picture elements (pixels), the teachings disclosed herein will apply.

(Block Diagram of Image Pickup Apparatus)

[0027]In FIG. 2, an image pickup apparat...

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Abstract

An image pickup apparatus includes a focus adjustment unit, an image sensor, a focus evaluation value calculation unit, and a control unit configured to drive the focus adjustment unit based on a focus evaluation value to perform an in-focus operation. A change curve representing a change amount of a focus evaluation value indicating a focusing state of an object image includes a first slope before inversion of a sign of an inclination of the change curve at a peak value on the change curve and a second slope after inversion of a sign of an inclination of the change curve at a peak value on the change curve. The control unit determines whether the focus evaluation value corresponding to the peak value on the change curve is used for the in-focus operation based on an inclination of the first slope and an inclination of the second slope.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to an image pickup apparatus for performing focus adjustment using an image signal acquired by an image sensor that photoelectrically converts an object image formed by an imaging optical system, and a method for controlling the same.[0003]2. Description of the Related Art[0004]In a digital still camera and video camera, automatic focusing (hereinafter referred to as AF) is conventionally performed by detecting a signal corresponding to a contrast of an object image detected by an image sensor and focusing on the object using a signal output from the image sensor. Well known examples image sensors include a charge coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS).[0005]In the above-mentioned method, the contrast of the object image needs to be sequentially detected while moving a focus lens along an optical axis over a predetermined movement range (a scanning operatio...

Claims

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Application Information

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IPC IPC(8): H04N5/232
CPCH04N5/23212H04N23/673H04N23/6811H04N23/635
InventorHAMANO, HIDEYUKI
OwnerCANON KK